In this context numerous mechanisms making it possible to provide this function are known. The majority of these mechanisms work on the basis of split-seconds pliers, which can be controlled by a column-wheel and allow to block or release the split-seconds pinion carrying the fly-back hand. This, however, entails a number of disadvantages, inter alia due to the fact that the working accuracy or the timing of the corresponding timepiece may vary depending on the working state of the fly-back hand. In fact, the energy required by the power source of the timepiece in order to drive the hands varies depending on the state of said split-seconds pliers, given that split-seconds pliers closed such as to stop the fly-back hand causes friction between the split-seconds lever and the split-seconds heart, which in conventional split-seconds mechanisms allow to return the fly-back hand into superposition with the corresponding hand. In order to overcome this problem, it is known in very high-class watch models to provide a lifting-lever mechanism allowing to lift the split-seconds lever when the split-seconds pliers are closed such as to isolate said lever from the split-seconds heart, however this is a complex and costly solution. In addition, this type of split-seconds mechanism necessitates to equip very thin arbors, such as the arbors carrying the chronograph hands, with hearts against which corresponding hammers tap repeatedly when the fly-back hand is to be re-synchronized with the corresponding hand. In the long term this increases the risk of damage to the mechanism. In addition, a split-seconds mechanism of this type considerably increases the complexity of the timepiece whilst adding, for example, in the case of application to a chronograph watch, solely the measurement of intermediate times without interruption of the main timing as an additional function.